This invention relates to a sealing arrangement for a rotary slide valve for an internal combustion engine which is subjected to fluctuating pressure in an adjacent pressure chamber, in particular, the combustion chamber of an internal combustion engine. More particularly, the invention is concerned with a profiled seal having a peripheral sliding surface which is applied against a counter surface of the slide valve and an associated sealing gasket for sealing a gap between the outer surface of the profiled seal and a slide valve housing. The profiled seal has at least one surface on which the combustion chamber pressure tends to move the seal in a direction toward the slide valve, and also includes means for making the sealing forces between the sliding surface and the counter surface substantially independent of fluctuations in the chamber pressure.
In a sealing arrangement for a rotary or cylindrical slide valve known from German patent No. 518,098 and having the characteristics indicated, which slide valve, for the purpose of cylinder charge changes, is placed ahead of the cylinder of a piston combustion engine, the profiled seal forms a displaceable cylinder bottom having a cylindrical sliding surface which is applied against the periphery of the rotary slide valve. The cylinder bottom has a large shoulder facing the combustion chamber so that it is pushed against the rotary slide valve by the pressures which fluctuate widely between the intake stroke and the expansion stroke. There results on the collaborating surfaces of the cylinder bottom and the rotary slide valve a large, widely fluctuating load which unfavorably affects the efficiency and useful life of the engine.
This disadvantage is alleviated to some extent in the known construction in that, via diaphragms, swivelling levers acted on by the cylinder pressures in such a manner that when the pressure increases, the levers exert a force on the cylinder bottom in the direction to lift it off the rotary slide valve. It is true that by this measure there is obtained a balancing of the forces of pressure resulting from the cylinder pressure exerted between the cylinder bottom and the rotary slide valve, but only to a limited extent and at a cost of production which is not justifiable. To this must be added an undesirable inertia of the diaphragm-swiveling lever arrangement.